Opto-electronics technologies have recently progressed by leaps and bounds due to the coming of the digital era, which also has stimulated the market for liquid crystal displays (LCDs). Liquid crystal displays possess many advantages, such as, for example, high display quality, small volume occupation, light weight, low driving voltage, and low power consumption. Therefore, liquid crystal displays are gradually replacing conventional cathode ray tube (CRT) displays and are applied widely to 3C (computers, communications, and consumer electronic) products, for example, personal digital assistants (PDAs), cellular phones, video recording units, notebook computers, desktop monitors, vehicular monitors, and projective televisions.
In general, the steps of turning off a liquid crystal display are controlled to turn off the backlight of the liquid crystal display, image data transmission, and power, in sequence. However, a residual image lingers for as long as several seconds on the panel of the liquid crystal display after the power is turned off. The phenomenon not only confuses users, but also impairs the display quality of the panel for a period of time. The residual image effect of a thin film transistor liquid crystal display (TFT-LCD), for example, is caused by the slow discharge rate of pixel electrodes of the thin film transistor liquid crystal display. As a result, charges in the pixel electrodes cannot discharge completely after power to the thin film transistor liquid crystal display is turned off. Consequently, complete discharge of residual charges in a liquid crystal cell or in capacitors takes longer.
Traditionally, the residual image effect is improved by modifying the manufacturing method of the liquid crystal displays. FIG. 1 shows an equivalent circuit diagram of a conventional thin film transistor liquid crystal display after turned off. Referring to FIG. 1, charges in a capacitor (CLCD) may discharge more quickly due to the lower resistance of a resistor (Roff) adjusted by modifying the manufacturing method. However, decreasing the resistance of the resistor (Roff) inevitably leads to high current (Ioff) according to the Ohm's law, which also results in a high leakage current in normal operation of the thin film transistor liquid crystal display.